/******************************************************************************
 *
 * Project:  Shapelib
 * Purpose:  Implementation of quadtree building and searching functions.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 1999, Frank Warmerdam
 * Copyright (c) 2012, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
 ******************************************************************************
 *
 */

#include "shapefil.h"

#include <math.h>
#include <assert.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

#ifdef USE_CPL
#include "cpl_error.h"
#endif

#ifndef TRUE
#define TRUE 1
#define FALSE 0
#endif

#ifndef bBigEndian
#if defined(CPL_LSB)
#define bBigEndian false
#elif defined(CPL_MSB)
#define bBigEndian true
#else
#ifndef static_var_bBigEndian_defined
#define static_var_bBigEndian_defined
static bool bBigEndian = false;
#endif
#endif
#endif

/* -------------------------------------------------------------------- */
/*      If the following is 0.5, nodes will be split in half.  If it    */
/*      is 0.6 then each subnode will contain 60% of the parent         */
/*      node, with 20% representing overlap.  This can be help to       */
/*      prevent small objects on a boundary from shifting too high      */
/*      up the tree.                                                    */
/* -------------------------------------------------------------------- */

#define SHP_SPLIT_RATIO 0.55

#ifdef __cplusplus
#define STATIC_CAST(type, x) static_cast<type>(x)
#define REINTERPRET_CAST(type, x) reinterpret_cast<type>(x)
#define CONST_CAST(type, x) const_cast<type>(x)
#define SHPLIB_NULLPTR nullptr
#else
#define STATIC_CAST(type, x) ((type)(x))
#define REINTERPRET_CAST(type, x) ((type)(x))
#define CONST_CAST(type, x) ((type)(x))
#define SHPLIB_NULLPTR NULL
#endif

/************************************************************************/
/*                          SHPTreeNodeInit()                           */
/*                                                                      */
/*      Initialize a tree node.                                         */
/************************************************************************/

static SHPTreeNode *SHPTreeNodeCreate(const double *padfBoundsMin,
                                      const double *padfBoundsMax)

{
    SHPTreeNode *psTreeNode;

    psTreeNode = STATIC_CAST(SHPTreeNode *, malloc(sizeof(SHPTreeNode)));
    if (SHPLIB_NULLPTR == psTreeNode)
        return SHPLIB_NULLPTR;

    psTreeNode->nShapeCount = 0;
    psTreeNode->panShapeIds = SHPLIB_NULLPTR;
    psTreeNode->papsShapeObj = SHPLIB_NULLPTR;

    psTreeNode->nSubNodes = 0;

    if (padfBoundsMin != SHPLIB_NULLPTR)
        memcpy(psTreeNode->adfBoundsMin, padfBoundsMin, sizeof(double) * 4);

    if (padfBoundsMax != SHPLIB_NULLPTR)
        memcpy(psTreeNode->adfBoundsMax, padfBoundsMax, sizeof(double) * 4);

    return psTreeNode;
}

/************************************************************************/
/*                           SHPCreateTree()                            */
/************************************************************************/

SHPTree SHPAPI_CALL1(*)
    SHPCreateTree(SHPHandle hSHP, int nDimension, int nMaxDepth,
                  const double *padfBoundsMin, const double *padfBoundsMax)

{
    SHPTree *psTree;

    if (padfBoundsMin == SHPLIB_NULLPTR && hSHP == SHPLIB_NULLPTR)
        return SHPLIB_NULLPTR;

    /* -------------------------------------------------------------------- */
    /*      Allocate the tree object                                        */
    /* -------------------------------------------------------------------- */
    psTree = STATIC_CAST(SHPTree *, malloc(sizeof(SHPTree)));
    if (SHPLIB_NULLPTR == psTree)
    {
        return SHPLIB_NULLPTR;
    }

    psTree->hSHP = hSHP;
    psTree->nMaxDepth = nMaxDepth;
    psTree->nDimension = nDimension;
    psTree->nTotalCount = 0;

    /* -------------------------------------------------------------------- */
    /*      If no max depth was defined, try to select a reasonable one     */
    /*      that implies approximately 8 shapes per node.                   */
    /* -------------------------------------------------------------------- */
    if (psTree->nMaxDepth == 0 && hSHP != SHPLIB_NULLPTR)
    {
        int nMaxNodeCount = 1;
        int nShapeCount;

        SHPGetInfo(hSHP, &nShapeCount, SHPLIB_NULLPTR, SHPLIB_NULLPTR,
                   SHPLIB_NULLPTR);
        while (nMaxNodeCount * 4 < nShapeCount)
        {
            psTree->nMaxDepth += 1;
            nMaxNodeCount = nMaxNodeCount * 2;
        }

#ifdef USE_CPL
        CPLDebug("Shape", "Estimated spatial index tree depth: %d",
                 psTree->nMaxDepth);
#endif

        /* NOTE: Due to problems with memory allocation for deep trees,
         * automatically estimated depth is limited up to 12 levels.
         * See Ticket #1594 for detailed discussion.
         */
        if (psTree->nMaxDepth > MAX_DEFAULT_TREE_DEPTH)
        {
            psTree->nMaxDepth = MAX_DEFAULT_TREE_DEPTH;

#ifdef USE_CPL
            CPLDebug(
                "Shape",
                "Falling back to max number of allowed index tree levels (%d).",
                MAX_DEFAULT_TREE_DEPTH);
#endif
        }
    }

    /* -------------------------------------------------------------------- */
    /*      Allocate the root node.                                         */
    /* -------------------------------------------------------------------- */
    psTree->psRoot = SHPTreeNodeCreate(padfBoundsMin, padfBoundsMax);
    if (SHPLIB_NULLPTR == psTree->psRoot)
    {
        free(psTree);
        return SHPLIB_NULLPTR;
    }

    /* -------------------------------------------------------------------- */
    /*      Assign the bounds to the root node.  If none are passed in,     */
    /*      use the bounds of the provided file otherwise the create        */
    /*      function will have already set the bounds.                      */
    /* -------------------------------------------------------------------- */
    if (padfBoundsMin == SHPLIB_NULLPTR)
    {
        SHPGetInfo(hSHP, SHPLIB_NULLPTR, SHPLIB_NULLPTR,
                   psTree->psRoot->adfBoundsMin, psTree->psRoot->adfBoundsMax);
    }

    /* -------------------------------------------------------------------- */
    /*      If we have a file, insert all its shapes into the tree.        */
    /* -------------------------------------------------------------------- */
    if (hSHP != SHPLIB_NULLPTR)
    {
        int iShape, nShapeCount;

        SHPGetInfo(hSHP, &nShapeCount, SHPLIB_NULLPTR, SHPLIB_NULLPTR,
                   SHPLIB_NULLPTR);

        for (iShape = 0; iShape < nShapeCount; iShape++)
        {
            SHPObject *psShape;

            psShape = SHPReadObject(hSHP, iShape);
            if (psShape != SHPLIB_NULLPTR)
            {
                SHPTreeAddShapeId(psTree, psShape);
                SHPDestroyObject(psShape);
            }
        }
    }

    return psTree;
}

/************************************************************************/
/*                         SHPDestroyTreeNode()                         */
/************************************************************************/

static void SHPDestroyTreeNode(SHPTreeNode *psTreeNode)

{
    int i;

    assert(SHPLIB_NULLPTR != psTreeNode);

    for (i = 0; i < psTreeNode->nSubNodes; i++)
    {
        if (psTreeNode->apsSubNode[i] != SHPLIB_NULLPTR)
            SHPDestroyTreeNode(psTreeNode->apsSubNode[i]);
    }

    if (psTreeNode->panShapeIds != SHPLIB_NULLPTR)
        free(psTreeNode->panShapeIds);

    if (psTreeNode->papsShapeObj != SHPLIB_NULLPTR)
    {
        for (i = 0; i < psTreeNode->nShapeCount; i++)
        {
            if (psTreeNode->papsShapeObj[i] != SHPLIB_NULLPTR)
                SHPDestroyObject(psTreeNode->papsShapeObj[i]);
        }

        free(psTreeNode->papsShapeObj);
    }

    free(psTreeNode);
}

/************************************************************************/
/*                           SHPDestroyTree()                           */
/************************************************************************/

void SHPAPI_CALL SHPDestroyTree(SHPTree *psTree)

{
    SHPDestroyTreeNode(psTree->psRoot);
    free(psTree);
}

/************************************************************************/
/*                       SHPCheckBoundsOverlap()                        */
/*                                                                      */
/*      Do the given boxes overlap at all?                              */
/************************************************************************/

int SHPAPI_CALL SHPCheckBoundsOverlap(const double *padfBox1Min,
                                      const double *padfBox1Max,
                                      const double *padfBox2Min,
                                      const double *padfBox2Max, int nDimension)
{
    for (int iDim = 0; iDim < nDimension; iDim++)
    {
        if (padfBox2Max[iDim] < padfBox1Min[iDim])
            return FALSE;

        if (padfBox1Max[iDim] < padfBox2Min[iDim])
            return FALSE;
    }

    return TRUE;
}

/************************************************************************/
/*                      SHPCheckObjectContained()                       */
/*                                                                      */
/*      Does the given shape fit within the indicated extents?          */
/************************************************************************/

static bool SHPCheckObjectContained(const SHPObject *psObject, int nDimension,
                                    const double *padfBoundsMin,
                                    const double *padfBoundsMax)

{
    if (psObject->dfXMin < padfBoundsMin[0] ||
        psObject->dfXMax > padfBoundsMax[0])
        return false;

    if (psObject->dfYMin < padfBoundsMin[1] ||
        psObject->dfYMax > padfBoundsMax[1])
        return false;

    if (nDimension == 2)
        return true;

    if (psObject->dfZMin < padfBoundsMin[2] ||
        psObject->dfZMax > padfBoundsMax[2])
        return false;

    if (nDimension == 3)
        return true;

    if (psObject->dfMMin < padfBoundsMin[3] ||
        psObject->dfMMax > padfBoundsMax[3])
        return false;

    return true;
}

/************************************************************************/
/*                         SHPTreeSplitBounds()                         */
/*                                                                      */
/*      Split a region into two subregion evenly, cutting along the     */
/*      longest dimension.                                              */
/************************************************************************/

static void SHPTreeSplitBounds(const double *padfBoundsMinIn,
                               const double *padfBoundsMaxIn,
                               double *padfBoundsMin1, double *padfBoundsMax1,
                               double *padfBoundsMin2, double *padfBoundsMax2)

{
    /* -------------------------------------------------------------------- */
    /*      The output bounds will be very similar to the input bounds,     */
    /*      so just copy over to start.                                     */
    /* -------------------------------------------------------------------- */
    memcpy(padfBoundsMin1, padfBoundsMinIn, sizeof(double) * 4);
    memcpy(padfBoundsMax1, padfBoundsMaxIn, sizeof(double) * 4);
    memcpy(padfBoundsMin2, padfBoundsMinIn, sizeof(double) * 4);
    memcpy(padfBoundsMax2, padfBoundsMaxIn, sizeof(double) * 4);

    /* -------------------------------------------------------------------- */
    /*      Split in X direction.                                           */
    /* -------------------------------------------------------------------- */
    if ((padfBoundsMaxIn[0] - padfBoundsMinIn[0]) >
        (padfBoundsMaxIn[1] - padfBoundsMinIn[1]))
    {
        double dfRange = padfBoundsMaxIn[0] - padfBoundsMinIn[0];

        padfBoundsMax1[0] = padfBoundsMinIn[0] + dfRange * SHP_SPLIT_RATIO;
        padfBoundsMin2[0] = padfBoundsMaxIn[0] - dfRange * SHP_SPLIT_RATIO;
    }

    /* -------------------------------------------------------------------- */
    /*      Otherwise split in Y direction.                                 */
    /* -------------------------------------------------------------------- */
    else
    {
        double dfRange = padfBoundsMaxIn[1] - padfBoundsMinIn[1];

        padfBoundsMax1[1] = padfBoundsMinIn[1] + dfRange * SHP_SPLIT_RATIO;
        padfBoundsMin2[1] = padfBoundsMaxIn[1] - dfRange * SHP_SPLIT_RATIO;
    }
}

/************************************************************************/
/*                       SHPTreeNodeAddShapeId()                        */
/************************************************************************/

static bool SHPTreeNodeAddShapeId(SHPTreeNode *psTreeNode, SHPObject *psObject,
                                  int nMaxDepth, int nDimension)

{
    int i;

    /* -------------------------------------------------------------------- */
    /*      If there are subnodes, then consider whether this object        */
    /*      will fit in them.                                               */
    /* -------------------------------------------------------------------- */
    if (nMaxDepth > 1 && psTreeNode->nSubNodes > 0)
    {
        for (i = 0; i < psTreeNode->nSubNodes; i++)
        {
            if (SHPCheckObjectContained(
                    psObject, nDimension,
                    psTreeNode->apsSubNode[i]->adfBoundsMin,
                    psTreeNode->apsSubNode[i]->adfBoundsMax))
            {
                return SHPTreeNodeAddShapeId(psTreeNode->apsSubNode[i],
                                             psObject, nMaxDepth - 1,
                                             nDimension);
            }
        }
    }

/* -------------------------------------------------------------------- */
/*      Otherwise, consider creating four subnodes if could fit into    */
/*      them, and adding to the appropriate subnode.                    */
/* -------------------------------------------------------------------- */
#if MAX_SUBNODE == 4
    else if (nMaxDepth > 1 && psTreeNode->nSubNodes == 0)
    {
        double adfBoundsMinH1[4], adfBoundsMaxH1[4];
        double adfBoundsMinH2[4], adfBoundsMaxH2[4];
        double adfBoundsMin1[4], adfBoundsMax1[4];
        double adfBoundsMin2[4], adfBoundsMax2[4];
        double adfBoundsMin3[4], adfBoundsMax3[4];
        double adfBoundsMin4[4], adfBoundsMax4[4];

        SHPTreeSplitBounds(psTreeNode->adfBoundsMin, psTreeNode->adfBoundsMax,
                           adfBoundsMinH1, adfBoundsMaxH1, adfBoundsMinH2,
                           adfBoundsMaxH2);

        SHPTreeSplitBounds(adfBoundsMinH1, adfBoundsMaxH1, adfBoundsMin1,
                           adfBoundsMax1, adfBoundsMin2, adfBoundsMax2);

        SHPTreeSplitBounds(adfBoundsMinH2, adfBoundsMaxH2, adfBoundsMin3,
                           adfBoundsMax3, adfBoundsMin4, adfBoundsMax4);

        if (SHPCheckObjectContained(psObject, nDimension, adfBoundsMin1,
                                    adfBoundsMax1) ||
            SHPCheckObjectContained(psObject, nDimension, adfBoundsMin2,
                                    adfBoundsMax2) ||
            SHPCheckObjectContained(psObject, nDimension, adfBoundsMin3,
                                    adfBoundsMax3) ||
            SHPCheckObjectContained(psObject, nDimension, adfBoundsMin4,
                                    adfBoundsMax4))
        {
            psTreeNode->nSubNodes = 4;
            psTreeNode->apsSubNode[0] =
                SHPTreeNodeCreate(adfBoundsMin1, adfBoundsMax1);
            psTreeNode->apsSubNode[1] =
                SHPTreeNodeCreate(adfBoundsMin2, adfBoundsMax2);
            psTreeNode->apsSubNode[2] =
                SHPTreeNodeCreate(adfBoundsMin3, adfBoundsMax3);
            psTreeNode->apsSubNode[3] =
                SHPTreeNodeCreate(adfBoundsMin4, adfBoundsMax4);

            /* recurse back on this node now that it has subnodes */
            return (SHPTreeNodeAddShapeId(psTreeNode, psObject, nMaxDepth,
                                          nDimension));
        }
    }
#endif /* MAX_SUBNODE == 4 */

/* -------------------------------------------------------------------- */
/*      Otherwise, consider creating two subnodes if could fit into     */
/*      them, and adding to the appropriate subnode.                    */
/* -------------------------------------------------------------------- */
#if MAX_SUBNODE == 2
    else if (nMaxDepth > 1 && psTreeNode->nSubNodes == 0)
    {
        double adfBoundsMin1[4], adfBoundsMax1[4];
        double adfBoundsMin2[4], adfBoundsMax2[4];

        SHPTreeSplitBounds(psTreeNode->adfBoundsMin, psTreeNode->adfBoundsMax,
                           adfBoundsMin1, adfBoundsMax1, adfBoundsMin2,
                           adfBoundsMax2);

        if (SHPCheckObjectContained(psObject, nDimension, adfBoundsMin1,
                                    adfBoundsMax1))
        {
            psTreeNode->nSubNodes = 2;
            psTreeNode->apsSubNode[0] =
                SHPTreeNodeCreate(adfBoundsMin1, adfBoundsMax1);
            psTreeNode->apsSubNode[1] =
                SHPTreeNodeCreate(adfBoundsMin2, adfBoundsMax2);

            return (SHPTreeNodeAddShapeId(psTreeNode->apsSubNode[0], psObject,
                                          nMaxDepth - 1, nDimension));
        }
        else if (SHPCheckObjectContained(psObject, nDimension, adfBoundsMin2,
                                         adfBoundsMax2))
        {
            psTreeNode->nSubNodes = 2;
            psTreeNode->apsSubNode[0] =
                SHPTreeNodeCreate(adfBoundsMin1, adfBoundsMax1);
            psTreeNode->apsSubNode[1] =
                SHPTreeNodeCreate(adfBoundsMin2, adfBoundsMax2);

            return (SHPTreeNodeAddShapeId(psTreeNode->apsSubNode[1], psObject,
                                          nMaxDepth - 1, nDimension));
        }
    }
#endif /* MAX_SUBNODE == 2 */

    /* -------------------------------------------------------------------- */
    /*      If none of that worked, just add it to this nodes list.         */
    /* -------------------------------------------------------------------- */
    psTreeNode->nShapeCount++;

    psTreeNode->panShapeIds =
        STATIC_CAST(int *, realloc(psTreeNode->panShapeIds,
                                   sizeof(int) * psTreeNode->nShapeCount));
    psTreeNode->panShapeIds[psTreeNode->nShapeCount - 1] = psObject->nShapeId;

    if (psTreeNode->papsShapeObj != SHPLIB_NULLPTR)
    {
        psTreeNode->papsShapeObj = STATIC_CAST(
            SHPObject **, realloc(psTreeNode->papsShapeObj,
                                  sizeof(void *) * psTreeNode->nShapeCount));
        psTreeNode->papsShapeObj[psTreeNode->nShapeCount - 1] = SHPLIB_NULLPTR;
    }

    return true;
}

/************************************************************************/
/*                         SHPTreeAddShapeId()                          */
/*                                                                      */
/*      Add a shape to the tree, but don't keep a pointer to the        */
/*      object data, just keep the shapeid.                             */
/************************************************************************/

int SHPAPI_CALL SHPTreeAddShapeId(SHPTree *psTree, SHPObject *psObject)

{
    psTree->nTotalCount++;

    return (SHPTreeNodeAddShapeId(psTree->psRoot, psObject, psTree->nMaxDepth,
                                  psTree->nDimension));
}

/************************************************************************/
/*                      SHPTreeCollectShapesIds()                       */
/*                                                                      */
/*      Work function implementing SHPTreeFindLikelyShapes() on a       */
/*      tree node by tree node basis.                                   */
/************************************************************************/

static void SHPTreeCollectShapeIds(SHPTree *hTree, SHPTreeNode *psTreeNode,
                                   double *padfBoundsMin, double *padfBoundsMax,
                                   int *pnShapeCount, int *pnMaxShapes,
                                   int **ppanShapeList)

{
    int i;

    /* -------------------------------------------------------------------- */
    /*      Does this node overlap the area of interest at all?  If not,    */
    /*      return without adding to the list at all.                       */
    /* -------------------------------------------------------------------- */
    if (!SHPCheckBoundsOverlap(psTreeNode->adfBoundsMin,
                               psTreeNode->adfBoundsMax, padfBoundsMin,
                               padfBoundsMax, hTree->nDimension))
        return;

    /* -------------------------------------------------------------------- */
    /*      Grow the list to hold the shapes on this node.                  */
    /* -------------------------------------------------------------------- */
    if (*pnShapeCount + psTreeNode->nShapeCount > *pnMaxShapes)
    {
        *pnMaxShapes = (*pnShapeCount + psTreeNode->nShapeCount) * 2 + 20;
        *ppanShapeList = STATIC_CAST(
            int *, realloc(*ppanShapeList, sizeof(int) * *pnMaxShapes));
    }

    /* -------------------------------------------------------------------- */
    /*      Add the local nodes shapeids to the list.                       */
    /* -------------------------------------------------------------------- */
    for (i = 0; i < psTreeNode->nShapeCount; i++)
    {
        (*ppanShapeList)[(*pnShapeCount)++] = psTreeNode->panShapeIds[i];
    }

    /* -------------------------------------------------------------------- */
    /*      Recurse to subnodes if they exist.                              */
    /* -------------------------------------------------------------------- */
    for (i = 0; i < psTreeNode->nSubNodes; i++)
    {
        if (psTreeNode->apsSubNode[i] != SHPLIB_NULLPTR)
            SHPTreeCollectShapeIds(hTree, psTreeNode->apsSubNode[i],
                                   padfBoundsMin, padfBoundsMax, pnShapeCount,
                                   pnMaxShapes, ppanShapeList);
    }
}

/************************************************************************/
/*                      SHPTreeFindLikelyShapes()                       */
/*                                                                      */
/*      Find all shapes within tree nodes for which the tree node       */
/*      bounding box overlaps the search box.  The return value is      */
/*      an array of shapeids terminated by a -1.  The shapeids will     */
/*      be in order, as hopefully this will result in faster (more      */
/*      sequential) reading from the file.                              */
/************************************************************************/

/* helper for qsort */
static int SHPTreeCompareInts(const void *a, const void *b)
{
    return *REINTERPRET_CAST(const int *, a) -
           *REINTERPRET_CAST(const int *, b);
}

int SHPAPI_CALL1(*)
    SHPTreeFindLikelyShapes(SHPTree *hTree, double *padfBoundsMin,
                            double *padfBoundsMax, int *pnShapeCount)

{
    int *panShapeList = SHPLIB_NULLPTR, nMaxShapes = 0;

    /* -------------------------------------------------------------------- */
    /*      Perform the search by recursive descent.                        */
    /* -------------------------------------------------------------------- */
    *pnShapeCount = 0;

    SHPTreeCollectShapeIds(hTree, hTree->psRoot, padfBoundsMin, padfBoundsMax,
                           pnShapeCount, &nMaxShapes, &panShapeList);

    /* -------------------------------------------------------------------- */
    /*      Sort the id array                                               */
    /* -------------------------------------------------------------------- */

    if (panShapeList != SHPLIB_NULLPTR)
        qsort(panShapeList, *pnShapeCount, sizeof(int), SHPTreeCompareInts);

    return panShapeList;
}

/************************************************************************/
/*                          SHPTreeNodeTrim()                           */
/*                                                                      */
/*      This is the recursive version of SHPTreeTrimExtraNodes() that   */
/*      walks the tree cleaning it up.                                  */
/************************************************************************/

static int SHPTreeNodeTrim(SHPTreeNode *psTreeNode)

{
    int i;

    /* -------------------------------------------------------------------- */
    /*      Trim subtrees, and free subnodes that come back empty.          */
    /* -------------------------------------------------------------------- */
    for (i = 0; i < psTreeNode->nSubNodes; i++)
    {
        if (SHPTreeNodeTrim(psTreeNode->apsSubNode[i]))
        {
            SHPDestroyTreeNode(psTreeNode->apsSubNode[i]);

            psTreeNode->apsSubNode[i] =
                psTreeNode->apsSubNode[psTreeNode->nSubNodes - 1];

            psTreeNode->nSubNodes--;

            i--; /* process the new occupant of this subnode entry */
        }
    }

    /* -------------------------------------------------------------------- */
    /*      If the current node has 1 subnode and no shapes, promote that   */
    /*      subnode to the current node position.                           */
    /* -------------------------------------------------------------------- */
    if (psTreeNode->nSubNodes == 1 && psTreeNode->nShapeCount == 0)
    {
        SHPTreeNode *psSubNode = psTreeNode->apsSubNode[0];

        memcpy(psTreeNode->adfBoundsMin, psSubNode->adfBoundsMin,
               sizeof(psSubNode->adfBoundsMin));
        memcpy(psTreeNode->adfBoundsMax, psSubNode->adfBoundsMax,
               sizeof(psSubNode->adfBoundsMax));
        psTreeNode->nShapeCount = psSubNode->nShapeCount;
        assert(psTreeNode->panShapeIds == SHPLIB_NULLPTR);
        psTreeNode->panShapeIds = psSubNode->panShapeIds;
        assert(psTreeNode->papsShapeObj == SHPLIB_NULLPTR);
        psTreeNode->papsShapeObj = psSubNode->papsShapeObj;
        psTreeNode->nSubNodes = psSubNode->nSubNodes;
        for (i = 0; i < psSubNode->nSubNodes; i++)
            psTreeNode->apsSubNode[i] = psSubNode->apsSubNode[i];
        free(psSubNode);
    }

    /* -------------------------------------------------------------------- */
    /*      We should be trimmed if we have no subnodes, and no shapes.     */
    /* -------------------------------------------------------------------- */
    return (psTreeNode->nSubNodes == 0 && psTreeNode->nShapeCount == 0);
}

/************************************************************************/
/*                       SHPTreeTrimExtraNodes()                        */
/*                                                                      */
/*      Trim empty nodes from the tree.  Note that we never trim an     */
/*      empty root node.                                                */
/************************************************************************/

void SHPAPI_CALL SHPTreeTrimExtraNodes(SHPTree *hTree)

{
    SHPTreeNodeTrim(hTree->psRoot);
}

/************************************************************************/
/*                              SwapWord()                              */
/*                                                                      */
/*      Swap a 2, 4 or 8 byte word.                                     */
/************************************************************************/

#ifndef SwapWord_defined
#define SwapWord_defined
static void SwapWord(int length, void *wordP)

{
    int i;

    for (i = 0; i < length / 2; i++)
    {
        unsigned char temp = STATIC_CAST(unsigned char *, wordP)[i];
        STATIC_CAST(unsigned char *, wordP)
        [i] = STATIC_CAST(unsigned char *, wordP)[length - i - 1];
        STATIC_CAST(unsigned char *, wordP)[length - i - 1] = temp;
    }
}
#endif

struct SHPDiskTreeInfo
{
    SAHooks sHooks;
    SAFile fpQIX;
};

/************************************************************************/
/*                         SHPOpenDiskTree()                            */
/************************************************************************/

SHPTreeDiskHandle SHPOpenDiskTree(const char *pszQIXFilename,
                                  const SAHooks *psHooks)
{
    SHPTreeDiskHandle hDiskTree;

    hDiskTree = STATIC_CAST(SHPTreeDiskHandle,
                            calloc(sizeof(struct SHPDiskTreeInfo), 1));

    if (psHooks == SHPLIB_NULLPTR)
        SASetupDefaultHooks(&(hDiskTree->sHooks));
    else
        memcpy(&(hDiskTree->sHooks), psHooks, sizeof(SAHooks));

    hDiskTree->fpQIX = hDiskTree->sHooks.FOpen(pszQIXFilename, "rb");
    if (hDiskTree->fpQIX == SHPLIB_NULLPTR)
    {
        free(hDiskTree);
        return SHPLIB_NULLPTR;
    }

    return hDiskTree;
}

/***********************************************************************/
/*                         SHPCloseDiskTree()                           */
/************************************************************************/

void SHPCloseDiskTree(SHPTreeDiskHandle hDiskTree)
{
    if (hDiskTree == SHPLIB_NULLPTR)
        return;

    hDiskTree->sHooks.FClose(hDiskTree->fpQIX);
    free(hDiskTree);
}

/************************************************************************/
/*                       SHPSearchDiskTreeNode()                        */
/************************************************************************/

static bool SHPSearchDiskTreeNode(SHPTreeDiskHandle hDiskTree,
                                  double *padfBoundsMin, double *padfBoundsMax,
                                  int **ppanResultBuffer, int *pnBufferMax,
                                  int *pnResultCount, int bNeedSwap,
                                  int nRecLevel)

{
    unsigned int i;
    unsigned int offset;
    unsigned int numshapes, numsubnodes;
    double adfNodeBoundsMin[2], adfNodeBoundsMax[2];
    int nFReadAcc;

    /* -------------------------------------------------------------------- */
    /*      Read and unswap first part of node info.                        */
    /* -------------------------------------------------------------------- */
    nFReadAcc = STATIC_CAST(
        int, hDiskTree->sHooks.FRead(&offset, 4, 1, hDiskTree->fpQIX));
    if (bNeedSwap)
        SwapWord(4, &offset);

    nFReadAcc += STATIC_CAST(int, hDiskTree->sHooks.FRead(adfNodeBoundsMin,
                                                          sizeof(double), 2,
                                                          hDiskTree->fpQIX));
    nFReadAcc += STATIC_CAST(int, hDiskTree->sHooks.FRead(adfNodeBoundsMax,
                                                          sizeof(double), 2,
                                                          hDiskTree->fpQIX));
    if (bNeedSwap)
    {
        SwapWord(8, adfNodeBoundsMin + 0);
        SwapWord(8, adfNodeBoundsMin + 1);
        SwapWord(8, adfNodeBoundsMax + 0);
        SwapWord(8, adfNodeBoundsMax + 1);
    }

    nFReadAcc += STATIC_CAST(
        int, hDiskTree->sHooks.FRead(&numshapes, 4, 1, hDiskTree->fpQIX));
    if (bNeedSwap)
        SwapWord(4, &numshapes);

    /* Check that we could read all previous values */
    if (nFReadAcc != 1 + 2 + 2 + 1)
    {
        hDiskTree->sHooks.Error("I/O error");
        return false;
    }

    /* Sanity checks to avoid int overflows in later computation */
    if (offset > INT_MAX - sizeof(int))
    {
        hDiskTree->sHooks.Error("Invalid value for offset");
        return false;
    }

    if (numshapes > (INT_MAX - offset - sizeof(int)) / sizeof(int) ||
        numshapes > INT_MAX / sizeof(int) - *pnResultCount)
    {
        hDiskTree->sHooks.Error("Invalid value for numshapes");
        return false;
    }

    /* -------------------------------------------------------------------- */
    /*      If we don't overlap this node at all, we can just fseek()       */
    /*      pass this node info and all subnodes.                           */
    /* -------------------------------------------------------------------- */
    if (!SHPCheckBoundsOverlap(adfNodeBoundsMin, adfNodeBoundsMax,
                               padfBoundsMin, padfBoundsMax, 2))
    {
        offset += numshapes * sizeof(int) + sizeof(int);
        hDiskTree->sHooks.FSeek(hDiskTree->fpQIX, offset, SEEK_CUR);
        return true;
    }

    /* -------------------------------------------------------------------- */
    /*      Add all the shapeids at this node to our list.                  */
    /* -------------------------------------------------------------------- */
    if (numshapes > 0)
    {
        if (*pnResultCount + numshapes >
            STATIC_CAST(unsigned int, *pnBufferMax))
        {
            int *pNewBuffer;

            *pnBufferMax = (*pnResultCount + numshapes + 100) * 5 / 4;

            if (STATIC_CAST(size_t, *pnBufferMax) > INT_MAX / sizeof(int))
                *pnBufferMax = *pnResultCount + numshapes;

            pNewBuffer = STATIC_CAST(
                int *, realloc(*ppanResultBuffer, *pnBufferMax * sizeof(int)));

            if (pNewBuffer == SHPLIB_NULLPTR)
            {
                hDiskTree->sHooks.Error("Out of memory error");
                return false;
            }

            *ppanResultBuffer = pNewBuffer;
        }

        if (hDiskTree->sHooks.FRead(*ppanResultBuffer + *pnResultCount,
                                    sizeof(int), numshapes,
                                    hDiskTree->fpQIX) != numshapes)
        {
            hDiskTree->sHooks.Error("I/O error");
            return false;
        }

        if (bNeedSwap)
        {
            for (i = 0; i < numshapes; i++)
                SwapWord(4, *ppanResultBuffer + *pnResultCount + i);
        }

        *pnResultCount += numshapes;
    }

    /* -------------------------------------------------------------------- */
    /*      Process the subnodes.                                           */
    /* -------------------------------------------------------------------- */
    if (hDiskTree->sHooks.FRead(&numsubnodes, 4, 1, hDiskTree->fpQIX) != 1)
    {
        hDiskTree->sHooks.Error("I/O error");
        return false;
    }
    if (bNeedSwap)
        SwapWord(4, &numsubnodes);
    if (numsubnodes > 0 && nRecLevel == 32)
    {
        hDiskTree->sHooks.Error("Shape tree is too deep");
        return false;
    }

    for (i = 0; i < numsubnodes; i++)
    {
        if (!SHPSearchDiskTreeNode(hDiskTree, padfBoundsMin, padfBoundsMax,
                                   ppanResultBuffer, pnBufferMax, pnResultCount,
                                   bNeedSwap, nRecLevel + 1))
            return false;
    }

    return true;
}

/************************************************************************/
/*                          SHPTreeReadLibc()                           */
/************************************************************************/

static SAOffset SHPTreeReadLibc(void *p, SAOffset size, SAOffset nmemb,
                                SAFile file)

{
    return STATIC_CAST(SAOffset, fread(p, STATIC_CAST(size_t, size),
                                       STATIC_CAST(size_t, nmemb),
                                       REINTERPRET_CAST(FILE *, file)));
}

/************************************************************************/
/*                          SHPTreeSeekLibc()                           */
/************************************************************************/

static SAOffset SHPTreeSeekLibc(SAFile file, SAOffset offset, int whence)

{
    return STATIC_CAST(SAOffset, fseek(REINTERPRET_CAST(FILE *, file),
                                       STATIC_CAST(long, offset), whence));
}

/************************************************************************/
/*                         SHPSearchDiskTree()                          */
/************************************************************************/

int SHPAPI_CALL1(*) SHPSearchDiskTree(FILE *fp, double *padfBoundsMin,
                                      double *padfBoundsMax, int *pnShapeCount)
{
    struct SHPDiskTreeInfo sDiskTree;
    memset(&sDiskTree.sHooks, 0, sizeof(sDiskTree.sHooks));

    /* We do not use SASetupDefaultHooks() because the FILE* */
    /* is a libc FILE* */
    sDiskTree.sHooks.FSeek = SHPTreeSeekLibc;
    sDiskTree.sHooks.FRead = SHPTreeReadLibc;

    sDiskTree.fpQIX = REINTERPRET_CAST(SAFile, fp);

    return SHPSearchDiskTreeEx(&sDiskTree, padfBoundsMin, padfBoundsMax,
                               pnShapeCount);
}

/***********************************************************************/
/*                       SHPSearchDiskTreeEx()                         */
/************************************************************************/

int *SHPSearchDiskTreeEx(SHPTreeDiskHandle hDiskTree, double *padfBoundsMin,
                         double *padfBoundsMax, int *pnShapeCount)

{
    int nBufferMax = 0;
    unsigned char abyBuf[16];
    int *panResultBuffer = SHPLIB_NULLPTR;

    *pnShapeCount = 0;

    /* -------------------------------------------------------------------- */
    /*	Establish the byte order on this machine.	  	        */
    /* -------------------------------------------------------------------- */
#if !defined(bBigEndian)
    {
        int i = 1;
        if (*REINTERPRET_CAST(unsigned char *, &i) == 1)
            bBigEndian = false;
        else
            bBigEndian = true;
    }
#endif

    /* -------------------------------------------------------------------- */
    /*      Read the header.                                                */
    /* -------------------------------------------------------------------- */
    hDiskTree->sHooks.FSeek(hDiskTree->fpQIX, 0, SEEK_SET);
    hDiskTree->sHooks.FRead(abyBuf, 16, 1, hDiskTree->fpQIX);

    if (memcmp(abyBuf, "SQT", 3) != 0)
        return SHPLIB_NULLPTR;

    bool bNeedSwap;
    if ((abyBuf[3] == 2 && bBigEndian) || (abyBuf[3] == 1 && !bBigEndian))
        bNeedSwap = false;
    else
        bNeedSwap = true;

    /* -------------------------------------------------------------------- */
    /*      Search through root node and its descendants.                   */
    /* -------------------------------------------------------------------- */
    if (!SHPSearchDiskTreeNode(hDiskTree, padfBoundsMin, padfBoundsMax,
                               &panResultBuffer, &nBufferMax, pnShapeCount,
                               bNeedSwap, 0))
    {
        if (panResultBuffer != SHPLIB_NULLPTR)
            free(panResultBuffer);
        *pnShapeCount = 0;
        return SHPLIB_NULLPTR;
    }
    /* -------------------------------------------------------------------- */
    /*      Sort the id array                                               */
    /* -------------------------------------------------------------------- */

    /* To distinguish between empty intersection from error case */
    if (panResultBuffer == SHPLIB_NULLPTR)
        panResultBuffer = STATIC_CAST(int *, calloc(1, sizeof(int)));
    else
        qsort(panResultBuffer, *pnShapeCount, sizeof(int), SHPTreeCompareInts);

    return panResultBuffer;
}

/************************************************************************/
/*                        SHPGetSubNodeOffset()                         */
/*                                                                      */
/*      Determine how big all the subnodes of this node (and their      */
/*      children) will be.  This will allow disk based searchers to     */
/*      seek past them all efficiently.                                 */
/************************************************************************/

static int SHPGetSubNodeOffset(SHPTreeNode *node)
{
    int i;
    int offset = 0;

    for (i = 0; i < node->nSubNodes; i++)
    {
        if (node->apsSubNode[i])
        {
            offset += 4 * sizeof(double) +
                      (node->apsSubNode[i]->nShapeCount + 3) * sizeof(int);
            offset += SHPGetSubNodeOffset(node->apsSubNode[i]);
        }
    }

    return (offset);
}

/************************************************************************/
/*                          SHPWriteTreeNode()                          */
/************************************************************************/

static void SHPWriteTreeNode(SAFile fp, SHPTreeNode *node,
                             const SAHooks *psHooks)
{
    int i, j;
    int offset;
    unsigned char *pabyRec;
    assert(SHPLIB_NULLPTR != node);

    offset = SHPGetSubNodeOffset(node);

    pabyRec = STATIC_CAST(unsigned char *,
                          malloc(sizeof(double) * 4 + (3 * sizeof(int)) +
                                 (node->nShapeCount * sizeof(int))));
    if (SHPLIB_NULLPTR == pabyRec)
    {
#ifdef USE_CPL
        CPLError(CE_Fatal, CPLE_OutOfMemory, "Memory allocation failure");
#endif
        assert(0);
        return;
    }

    memcpy(pabyRec, &offset, 4);

    /* minx, miny, maxx, maxy */
    memcpy(pabyRec + 4, node->adfBoundsMin + 0, sizeof(double));
    memcpy(pabyRec + 12, node->adfBoundsMin + 1, sizeof(double));
    memcpy(pabyRec + 20, node->adfBoundsMax + 0, sizeof(double));
    memcpy(pabyRec + 28, node->adfBoundsMax + 1, sizeof(double));

    memcpy(pabyRec + 36, &node->nShapeCount, 4);
    j = node->nShapeCount * sizeof(int);
    if (j)
        memcpy(pabyRec + 40, node->panShapeIds, j);
    memcpy(pabyRec + j + 40, &node->nSubNodes, 4);

    psHooks->FWrite(pabyRec, 44 + j, 1, fp);
    free(pabyRec);

    for (i = 0; i < node->nSubNodes; i++)
    {
        if (node->apsSubNode[i])
            SHPWriteTreeNode(fp, node->apsSubNode[i], psHooks);
    }
}

/************************************************************************/
/*                            SHPWriteTree()                            */
/************************************************************************/

int SHPAPI_CALL SHPWriteTree(SHPTree *tree, const char *filename)
{
    SAHooks sHooks;

    SASetupDefaultHooks(&sHooks);

    return SHPWriteTreeLL(tree, filename, &sHooks);
}

/************************************************************************/
/*                           SHPWriteTreeLL()                           */
/************************************************************************/

int SHPWriteTreeLL(SHPTree *tree, const char *filename, const SAHooks *psHooks)
{
    const char signature[4] = "SQT";
    char abyBuf[32];
    SAFile fp;

    SAHooks sHooks;
    if (psHooks == SHPLIB_NULLPTR)
    {
        SASetupDefaultHooks(&sHooks);
        psHooks = &sHooks;
    }

    /* -------------------------------------------------------------------- */
    /*      Open the output file.                                           */
    /* -------------------------------------------------------------------- */
    fp = psHooks->FOpen(filename, "wb");
    if (fp == SHPLIB_NULLPTR)
    {
        return FALSE;
    }

    /* -------------------------------------------------------------------- */
    /*	Establish the byte order on this machine.	  	        */
    /* -------------------------------------------------------------------- */
#if !defined(bBigEndian)
    {
        int i = 1;
        if (*REINTERPRET_CAST(unsigned char *, &i) == 1)
            bBigEndian = false;
        else
            bBigEndian = true;
    }
#endif

    /* -------------------------------------------------------------------- */
    /*      Write the header.                                               */
    /* -------------------------------------------------------------------- */
    memcpy(abyBuf + 0, signature, 3);

    if (bBigEndian)
        abyBuf[3] = 2; /* New MSB */
    else
        abyBuf[3] = 1; /* New LSB */

    abyBuf[4] = 1; /* version */
    abyBuf[5] = 0; /* next 3 reserved */
    abyBuf[6] = 0;
    abyBuf[7] = 0;

    psHooks->FWrite(abyBuf, 8, 1, fp);

    psHooks->FWrite(&(tree->nTotalCount), 4, 1, fp);

    /* write maxdepth */

    psHooks->FWrite(&(tree->nMaxDepth), 4, 1, fp);

    /* -------------------------------------------------------------------- */
    /*      Write all the nodes "in order".                                 */
    /* -------------------------------------------------------------------- */

    SHPWriteTreeNode(fp, tree->psRoot, psHooks);

    psHooks->FClose(fp);

    return TRUE;
}
